Image reading apparatus that reads originals, control method therefor, and storage medium

ABSTRACT

An image reading apparatus which is capable of preventing occurrence of a paper jam and poor stacking during conveyance of originals. The image reading apparatus sets a type of an original, conveys the original based on the set type of the original, and reads an image on the conveyed original. An original detecting sensor detects placement of the original on an original tray. An LCD touch panel displays an object for setting a type of the original in response to the detection by the original detecting sensor.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an image reading apparatus, a controlmethod therefor, and a storage medium.

Description of the Related Art

An image forming apparatus that reads originals conveyed from anautomatic original conveying device is known. In the image formingapparatus, when an original is read, a variety of problems occur,depending on a thickness of the original. For example, when an originalconveyed from the automatic original conveying device is a thick sheet,a high load is applied to conveying rollers in a curved area of aconveying path, causing a paper jam. When an original conveyed from theautomatic original conveying device is a thin sheet, it takes time for adischarged original to drop entirely onto a sheet discharging unitbecause the original itself is light in weight, and hence a trailing endof the original hits a leading end of a succeeding original, causing apaper jam or poor stacking. Conventionally, to prevent occurrence of apaper jam and poor stacking during conveyance of an original asdescribed above, a thickness of the original is detected by a sensor,and a conveying speed of the original is controlled according to thedetected thickness (see, for example, Japanese Laid-Open PatentPublication (Kokai) No. H06-24604).

There is another problem that when an original read by the image formingapparatus is a thin sheet, letters or images on the reverse side showthrough, and image data or printed matter with the letters or images onthe reverse side showing through (hereafter referred to as “show-throughdata”) is output. To address this problem, an image forming apparatuswith a show-through prevention function has been developed. When theshow-through prevention function is enabled by user's setting, thisimage forming apparatus performs image processing on scanned-in imagedata to remove show-through.

The setting on the show-through prevention function is configured by auser, but the user does not notice that letters or images on the reverseside show through until he or she actually sees image data or printedmatter that has been output. For this reason, when an original to beread is a thin sheet, reading is started often before the show-throughprevention function is enabled. As a result, output of show-through datacannot be reliably prevented even though occurrence of a paper jam andpoor stacking during conveyance of an original can be prevented.

SUMMARY OF THE INVENTION

The present invention provides an image reading apparatus and a controlmethod therefor, which are capable of preventing occurrence of a paperjam and poor stacking during conveyance of an original, as well as astorage medium.

Accordingly, the present invention provides an image reading apparatusincluding an original tray, a setting unit that sets a type of anoriginal, a conveyance control unit that controls conveyance of thedocument by a conveying unit based on the type of the original set bythe setting unit, and a reading unit that reads an image on the originalconveyed by the conveying unit, comprising a detecting unit configuredto detect that the original has been placed on the original tray, and adisplay unit configured to display an object for setting a type of theoriginal in response to the detecting unit detecting that the originalhas been placed on the original tray.

According to the present invention, occurrence of a paper jam and poorstacking is prevented during conveyance of an original.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments (with reference to theattached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external view of an image forming apparatus which is animage reading apparatus according to an embodiment of the presentinvention.

FIG. 2 is a cross-sectional view schematically showing arrangements ofan ADF and an image reading unit in FIG. 1.

FIG. 3 is a block diagram schematically showing an arrangement of theimage forming apparatus in FIG. 1.

FIG. 4 is a function block diagram showing functions for implementingshow-through removal by an image processing circuit in FIG. 3.

FIG. 5 is an external view of an operating unit in FIG. 3.

FIG. 6A is a view showing an example of a copy screen which is displayedon an LCD touch panel in FIG. 5.

FIG. 6B is a view showing an example of a show-through preventionsetting screen which is displayed on the LCD touch panel in FIG. 5.

FIG. 6C is a view showing an example of a thickness selection screenwhich is displayed on the LCD touch panel in FIG. 5.

FIG. 7 is a flowchart showing the procedure of a scanning controlprocess which is carried out by a controller unit in FIG. 3.

FIGS. 8A and 8B are views showing examples of a notification screenwhich is displayed on the LCD touch panel in FIG. 5.

FIG. 9 is a flowchart showing the procedure of a scanning process whichis carried out by the image reading unit in FIG. 3.

FIG. 10 is a flowchart showing the procedure of show-through removalimage processing which is carried out by the controller unit in FIG. 3.

FIGS. 11A to 11C are views useful in explaining how a base color levelis determined in step S1004 in FIG. 10.

DESCRIPTION OF THE EMBODIMENTS

An embodiment of the present invention will now be described in detailwith reference to the drawings. FIG. 1 is an external view of an imageforming apparatus 100 which is an image reading apparatus according toan embodiment of the present invention. The image forming apparatus 100has an automatic document feeding unit 101, an image reading unit 103,and an image forming unit 104. It should be noted that in the followingdescription, the automatic document feeding unit 101 will be referred toas the ADF 101.

In the image forming apparatus 100, when a user places originals on anoriginal tray 102 of the ADF 101 and uses an operating unit 326 in FIG.3, which will be described later, to issue an instruction to startreading, a controller unit 321 in FIG. 3, which will be described later,sends an original reading instruction to the image reading unit 103. Inaccordance with the received original reading instruction, the imagereading unit 103 feeds the originals one by one from the original tray102 of the ADF 101 and reads the originals. The image forming apparatus100 is also capable of reading an original placed on an original platenglass 221 in FIG. 2, which will be described later.

The image reading unit 103 causes an illumination lamp (not shown) toemit light and inputs reflected light, which has been obtained byscanning an image on an original by exposing it to light, to a linearimage sensor (CCD sensor) (not shown), thus converting information ofthe image into an electric signal. The image reading unit 103 alsoconverts the electric signal thus obtained into a luminance signalcomprised of colors R, G, and B and outputs the luminance signal asimage data to a controller unit 321, which will be described later.

The image forming unit 104 is an image forming device that forms theimage data received from the controller unit 321, which will bedescribed later, on a sheet. In the present embodiment, anelectrophotographic method using a photosensitive drum (not shown) and aphotosensitive belt (not shown) is adopted as an image forming method.The image forming unit 104 has a sheet feeding unit 105, a sheetdischarging unit 106, and a finisher unit 107. The sheet feeding unit105 has a plurality of cassettes storing sheets of different sizes indifferent orientations. Printed matter is discharged to the sheetdischarging unit 106 and the finisher unit 107.

FIG. 2 is a cross-sectional view schematically showing arrangements ofthe ADF 101 and the image reading unit 103 in FIG. 1. It should be notedthat in FIG. 2, their internal arrangements are seen through for ease ofunderstanding.

Referring to FIG. 2, the ADF 101 has an original tray 201, a separationpad 202, an original detecting sensor 203, a ranging sensor 204, aseparation sensor 205, and a sheet feeding roller 206. A batch oforiginals S comprised of one or more sheets is stacked on the originaltray 201. The separation pad 202 prevents the batch of originals S fromjutting out the original tray 201 and moving downstream beforeconveyance thereof is started. The original detecting sensor 203 detectsplacement of originals on the original tray 201. The ranging sensor 204measures the distance from the uppermost surface of the batch oforiginals S. The separation sensor 205 detects that an original haspassed the separation roller 207.

The sheet feeding roller 206 moves down to and rotates on a surface ofthe batch of originals S stacked on the original tray 201. As a result,the uppermost one of the originals conveyed by the sheet feeding roller206 is separated from the other ones by the action of the separationroller 207 and the sheet feeding roller 206. The separation isimplemented via, for example, a retard separation technique. It shouldbe noted that in a case where the separation sensor 205 has detected nooriginal for a predetermined time period (t1) since the start ofconveyance, the ADF 101 stops driving the sheet feeding roller 206 andothers. The predetermined time period (t1) is determined withconsideration given to a time period required for an original to reachthe separation sensor 205 after the start of conveyance and a delayestimated based on a conveying speed.

The original separated by the action of the separation roller 207 andthe separation pad 202 is conveyed to a registration roller 209 byconveying rollers 208 and abuts against the registration roller 209.This loops the original to correct for a skew of the original beingconveyed. A sheet feeding path on which the original that has passed theregistration roller 209 is conveyed toward a flow reading glass 210 islocated downstream of the registration roller 209.

The original that has been conveyed to the sheet feeding path isconveyed onto a platen by a large roller 211 and a conveying roller 212.The large roller 211 comes into contact with the flow reading glass 210.The original that has been conveyed by the large roller 211 passes aconveying roller 213, moves between a roller 214 and a moving glass andis discharged onto a discharged original tray 216 via a sheetdischarging flapper and sheet discharging rollers 215.

In the present embodiment, the ADF 101 reads an image on a reverse sideof an original by flipping it upside down. The ADF 101 moves theoriginal to an inverting path 217 by reversing the rotating direction ofthe sheet discharging rollers 215 and switches the sheet dischargingflapper while keeping the original held between the sheet dischargingrollers 215. Skewing of the original during conveyance is corrected forby causing the moved original to abut against the registration roller209 via the inverting path 217 and looping the original again. Afterthat, the ADF 101 causes the conveying roller 212 and the large roller211 to move the original to the flow reading glass 210 again so that thereverse side of the original can be read by the flow reading glass 210.

The original tray 201 is equipped with a guide restriction plate 218that is capable of sliding in a sub scanning direction of the stackedbatch of originals S, and an original width sensor (not shown) thatdetects a width of the originals S in response to movement of the guiderestriction plate 218. A size of the batch of originals S stacked on theoriginal tray 201 is determined by the original width sensor and apre-registration sensor 219. An original length detection sensor (notshown) provided on a conveying path of the ADF 101 detects an originallength based on a distance over which an original is conveyed until itstrailing end is detected after its leading end is detected. The originalsize is determined based on the original length and the result ofdetection by the original width detection sensor.

The image reading unit 103 optically reads image information recorded onthe original placed on the original platen glass 221 by scanning it withan optical scanner unit 220 in the sub scanning direction (see an arrowA in FIG. 2). It should be noted that originals placed on the ADF 101are conveyed one by one to a reading center position in the ADF 101. Atthis time, the optical scanner unit 220 is moved to the reading centerposition to read the original at the reading center position. Originalsplaced on the ADF 101 or an original placed on the original platen glass221 is read by an optical system. The optical system is comprised of theflow reading glass 210, the original platen glass 221, the opticalscanner unit 220, mirrors 222 and 223, a lens 224, and a CCD sensor unit225. The optical scanner unit 220 is equipped with a lamp 226 and amirror 227. The image information read by the optical system issubjected to photoelectrical conversion and output as image data to thecontroller unit 321, which will be described later. A white board 228provided in the image reading unit 103 creates reference data forshading white level. In the present embodiment, The CCD sensor unit 225is comprised of a color CCD 229 and a monochrome CCD 230.

FIG. 3 is a block diagram schematically showing an arrangement of theimage forming apparatus 100 in FIG. 1. Referring to FIG. 3, the ADF 101has a CPU 300, a ROM 301, a RAM 302, a motor 303, sensors 304, asolenoid 306, and a clutch 307. The CPU 300, the ROM 301, the RAM 302,the motor 303, the sensor 304, the solenoid 306, and the clutch 307 areconnected to one another via a bus 308. The ADF 101 also has an inputport (not shown) and an output port (not shown). The sensors 304 whichrepresent the sensors in FIG. 2 are connected to the input port. Themotor 303, the solenoid 306, and the clutch 307 which drive the rollersfor conveyance in FIG. 2 are connected to the output port.

The CPU 300 controls sheet conveyance in accordance with a controlprogram stored in the ROM 301. The CPU 300 carries out serialcommunications with a CPU 310 of the image reading unit 103 via acontrol communication line 309 and sends and receives control data toand from the image reading unit 103. For example, the CPU 300 sends animage leading-end signal, which is a reference for a leading end oforiginal image data, to the image reading unit 103. The CPU 300 alsoreceives control data from the CPU 310 of the image reading unit 103,and in accordance with the received control data, sends a result ofdetection by the sensor 304 to the image reading unit 103. The ROM 301stores control programs and fixed parameters. The RAM 302 stores inputdata and work data.

The image reading unit 103 has the CPU 310, a ROM 311, a RAM 312, asheet interval correction unit 313, an image processing unit 314, anoptical system motor drive unit 315, a lamp 226, a CCD sensor unit 225,and an image memory 316. The CPU 310, the ROM 311, the RAM 312, thesheet interval correction unit 313, the image processing unit 314, theoptical system motor drive unit 315, and the lamp 226 are connected toone another via a bus 320. The image processing unit 314 is connected tothe CCD sensor unit 225 and the image memory 316.

The CPU 310 performs all types of control relating to the image readingunit 103. The ROM 311 stores programs. The RAM 312 is a nonvolatilestorage device and is used as, for example, a work area for the CPU 310.The sheet interval correction unit 313 corrects a sheet interval. Theoptical system motor drive unit 315 is a driver circuit for driving anoptical system drive motor. The CPU 310 carries out an image readingprocess by controlling the optical system motor drive unit 315 andcausing the image processing unit 314 to control the CCD sensor unit225.

To implement sheet conveyance, the CPU 310 sends a command relating tosheet conveyance control to the CPU 300 of the ADF 101. The CPU 300 thathas received the command monitors the sensor 304 placed on the conveyingpath and drives the conveyance motor 303, the solenoid 306, and theclutch 307 to implement sheet conveyance. Thus, the CPU 310 controlssheet conveyance by the ADF 101 and image reading by the image readingunit 103.

An image signal that has passed the lens 224 and formed an image on theCCD sensor unit 225 is converted into digital image data. The digitalimage data thus obtained is subjected to various types of imageprocessing by the image processing unit 314, such as a shading processand a process in which a streak in image data is detected and correctedfor, and then written into the image memory 316. The data written intothe image memory 316 is then sent to the controller unit 321 via animage communication line 317. An image leading-end signal, which is areference for a leading end of original image data, has its notificationtiming adjusted by the CPU 310 and is sent to the controller unit 321via a control communication line 318. Similarly, an image tip signalreceived from the ADF 101 has its notification timing adjusted by theCPU 310 and is sent to the controller unit 321 via the controlcommunication line 318.

The CPU 310 controls the image processing unit 314. The CPU 310 controlsthe CCD sensor unit 225 by transmitting a control signal to the CCDsensor unit 225 via the image processing unit 314. In a process ofscanning an original image with CCD sensor unit 225, the color CCD 229and the monochrome CCD 230 read analog image signals. The line-by-lineanalog image signals that have been read are output to a CCD controlunit 319. The CCD control unit 319 converts the received analog imagesignals into digital image data and outputs the digital image data tothe image memory 316. The image memory 316 sends the received digitalimage data to the controller unit 321 via the image communication line317.

The CPU 310 carries out serial communications with the CPU 322 of thecontroller unit 321 via the control communication line 318 and sends andreceives control data to and from the controller unit 321. Based on thecontrol data received from the CPU 322, the CPU 310 detects a shapeabnormality of an original being conveyed. To detect a shapeabnormality, the CPU 310 calculates a difference between a distance tothe uppermost surface of the batch of originals S measured before thestart of conveyance and a distance to the uppermost surface of the batchof originals S measured after the lapse of a predetermined time period(t2) since the start of conveyance with respect to each original. Whenthe difference is equal to or longer than a predetermined distance (d1),the CPU 310 determines that the original has a shape abnormality andnotifies the CPU 322 of the determination result.

The controller unit 321 controls the entire image forming apparatus 100including the ADF 101, the image reading unit 103, and the image formingunit 104. The controller unit 321 has a CPU 322, an image processingcircuit 323, a scanner I/F 324, an image memory 325, an operating unit326, a RAM 327, a ROM 328, a printer I/F 329, and an HDD 330. The CPU322, the image processing circuit 323, the scanner I/F 324, the imagememory 325, the operating unit 326, the RAM 327, the ROM 328, theprinter I/F 329, and the HDD 330 are connected to one another via a bus331. The CPU 322 loads programs stored in the HDD 330 into the RAM 327and executes the loaded programs. The RAM 327 is a nonvolatile storagedevice and is used as, for example, a work area for the CPU 322. The ROM328 stores programs. The controller unit 321 stores image data, which isreceived from the image reading unit 103 via the image communicationline 317, in the image memory 325.

The image processing circuit 323 converts the image data stored in theimage memory 325 into an image. The image processing circuit 323subjects the image data to, for example, a rotation process, aresolution conversion process, a zooming process, and a color spaceconversion process. The rotation process is a process in which an imagecomprised of 32×32 pixels is rotated through a designated angle. Theresolution conversion process is a process in which a resolution of animage is converted. The zooming process is a process in which an imageis zoomed in or out. The color space conversion process is a process inwhich a multi-valued input image is subjected to a matrix operation, anda YUV image is converted into a Lab image based on LUT. In the colorspace conversion process, base removal and show-through removal areimplemented due to its 3×8 matrix operation and one-dimensional LUT. Theimage processing circuit 323 returns the converted image data back tothe image memory 325.

FIG. 4 is a function block diagram showing functions for implementingshow-through removal in the image processing circuit 323 in FIG. 3. Inthe present embodiment, the image processing circuit 323 removesshow-through by determining a base color level in image data, performinga computation for removing a base color corresponding to the base colorlevel, and converting an input luminance value to an output luminancevalue. When an original is pulled into a feeder and starts to be read bythe CCD sensor unit 225, an image signal generating module 401 convertsthe read image into a luminance signal and outputs the luminance signalto a histogram generating module 402. The histogram generating module402 generates a histogram by extracting pixels at an arbitrary samplingpitch based on the received signal to count a luminance level. It shouldbe noted that in a case where the original size has not been identifieduntil the start of scanning, the image signal generating module 401performs processing based on the greatest conceivable image length.

In the image processing circuit 323, when the original size isdetermined while an image signal is being generated, an original sizedetecting module 403 notifies a histogram generating region changingmodule 404 of the original size. The histogram generating regionchanging module 404 changes a region for image data sampled by thehistogram generating module 402 to the original size which it has beennotified of by the original size detecting module 403. After theoriginal is scanned, a base color level determination module 405determines a base color level from the histogram sampled by thehistogram generating module 402. Based on the determined base colorlevel, the base color level determination module 405 sets a base colorremoval coefficient in a base color removal process module 406. The basecolor removal process module 406 carries out a process in which itremoves the base color from the image data based on the set coefficient.

Referring again to FIG. 3, the image forming unit 104 conveys arecording sheet, prints image data as a visible image on the recordingsheet, and discharges printed matter from the image forming apparatus100. The image forming unit 104 has a control unit 332 and a markingunit 333 as well as the sheet feeding unit 105, the sheet dischargingunit 106, and the finisher unit 107 in FIG. 1. The control unit 332, themarking unit 333, the sheet discharging unit 106, and the sheet feedingunit 105 are connected to one another via a bus 334. The control unit332 controls the image forming unit 104. When the marking unit 333 isready to form an image, the control unit 332 sends an image tip signalto the controller unit 321 via the control communication line 335. Thesheet discharging unit 106 has a function of discharges printed matterfrom the image forming apparatus 100. The marking unit 333 a function oftransferring image data onto a sheet and fixing the same. The markingunit 333 transfers image data received via the image communication line336 onto a sheet and fixes the same. The finisher unit 107 performspunching and sorting.

FIG. 5 is an external view of the operating unit 326 in FIG. 3. Theoperating unit 326 has an LCD touch panel 500, a numeric keypad 501, anID key 502, a reset key 503, a guide key 504, a user mode key 505, aninterrupt key 506, a start key 507, a stop key 508, a power saving key509, a counter check key 510, an LED 511, an error LED 512, and a powerLED 513.

The LCD touch panel 500 is an input device comprised of a liquid crystaldisplay onto which a touch panel is attached. Functions for use inoperating the image forming apparatus 100, image data, and so forth aredisplayed on the LCD touch panel 500. The numeric keypad 501 iscomprised of hard keys for inputting numeric values from 0 to 9. The IDkey 502 is used to input a division number and an encryption code in acase where the image forming apparatus 100 is managed on adivision-by-division basis. The reset key 503 is a hard key forresetting a mode that has been set. The guide key 504 is a hard key fordisplaying screens explaining respective modes installed in the imageforming apparatus 100. The user mode key 505 is a hard key fordisplaying a user mode screen on the LCD touch panel 500. On the usermode screen, user-specific settings on the image forming apparatus 100can be configured.

The interrupt key 506 is a hard key for making an interrupt copy. Thestart key 507 is a hard key for starting copying or scanning. The stopkey 508 is a hard key for canceling a job being executed. The powersaving key 509 is a hard key for shifting the image forming apparatus100 into a power saving state or returning the image forming apparatus100 from the power saving state. The counter check key 510 is a hard keyfor displaying a count screen on the LCD touch panel 500. A resultobtained by counting the number of copy sheets that have been used isdisplayed on the count screen. The LED 511 lights up when the imageforming apparatus 100 is running, for example, when the image formingapparatus 100 is executing a job or carrying out a process in which itaccumulates images in the image memory 325. The error LED 512 lights upwhen an error such as a paper jam or door open is occurring in the imageforming apparatus 100. The power LED 513 lights up when a main switch ofthe image forming apparatus 100 is on.

FIG. 6A is a view showing an example of a copy screen 600 which isdisplayed on the LCD touch panel 500 in FIG. 5. FIG. 6B is a viewshowing an example of a show-through prevention setting screen 609 whichis displayed on the LCD touch panel 500 in FIG. 5. FIG. 6C is a viewshowing an example of a thickness selection screen 614 which isdisplayed on the LCD touch panel 500 in FIG. 5.

Referring to FIG. 6A, buttons for canine basic functions of the imageforming apparatus 100, for example, a color selection button 601, a zoombutton 602, and a sheet selection button 603 are placed on the copyscreen 600. Setting statuses relating to functions corresponding to therespective buttons are displayed in a display field 604. Other functionbutton 605 is also placed on the copy screen 600. By selecting the otherfunction button 605, the user is able to configure settings on functionsother than the basic functions, for example, settings on such functionas page printing, page aggregation, and bookbinding. Shortcut buttonsfor calling functions frequently used by the user, for example, adouble-sided button 606, a finish button 607, and a show-throughprevention button 608 are also placed on the copy screen 600. Thedouble-sided button 606 is a button for configuring settings ondouble-sided printing. The finish button 607 is a button for configuringsettings on an output mode for printing and post-processing. Theshow-through prevention button 608 is a button for configuring settingson a show-through prevention function of preventing show-through when anoriginal is read. When the user selects the show-through preventionbutton 608, the show-through prevention setting screen 609 in FIG. 6B isdisplayed in a manner overlapping the copy screen 600.

The show-through prevention setting screen 609 is comprised of an ONbutton 610, an OFF button 611, an OK button 612, and a cancel button613. The ON button 610 is a button for enabling the show-throughprevention function. The OFF button 611 is a button for disabling theshow-through prevention function. When, for example, the user depressesthe OK button 612 on the show-through prevention setting screen 609 in astate where the ON button 610 is selected, the show-through preventionfunction of the image forming apparatus 100 is enabled. When the userdepresses the OK button 612 in a state where the OFF button 611 isselected, the show-through prevention function of the image formingapparatus 100 is disabled. On the other hand, when the user depressesthe cancel button 613, the show-through prevention setting screen 609 isclosed without the setting on the show-through prevention function beingconfigured.

The thickness selection screen 614 in FIG. 6C is also displayed on theLCD touch panel 500 when the original detecting sensor 203 senses anoriginal. On the thickness selection screen 614, a thickness of theoriginal detected by the original detecting sensor 203 is set by theuser. Buttons for setting a thickness of an original, for example, athick sheet button 615, a regular button 616, and a thin sheet button617 are placed on the thickness selection screen 614. It should be notedthat in the present embodiment, a thickness of an original whichcorresponds to the thick sheet button 615 is, for example, 220 g/m², athickness of an original which corresponds to the regular button 616 is,for example, 64 to 128 or 157 g/m², and a thickness of an original whichcorresponds to the thin sheet button 617 is, for example, 37, 42, or 52g/m². An OK button 618 is also displayed on the thickness selectionscreen 614. When the user depresses the OK button 618 in a state inwhich any of the thick sheet button 615, the regular button 616, and thethin sheet button 617 is selected, a thickness corresponding to theselected button is set as the thickness of the original detected by theoriginal detecting sensor 203.

FIG. 7 is a flowchart showing the procedure of a scanning controlprocess which is carried out by the controller unit 321 in FIG. 3. Theprocess in FIG. 7 is implemented by the CPU 322 of the controller unit321 executing a program expanded from the ROM 328 into the RAM 327. Itis assumed that in the process in FIG. 7, the copy screen 600 isdisplayed on the LCD touch panel 500.

Referring to FIG. 7, based on a notification from the original detectingsensor 203, the CPU 322 determines whether or not any original is placedon the ADF 101 (step S701).

As a result of the determination in the step S701, when no original isplaced on the ADF 101, the CPU 322 carries out a process in step S711,which will be described later. As a result of the determination in thestep S701, when any original is placed on the ADF 101, the CPU 322displays the thickness selection screen 614 on the LCD touch panel 500(step S702). When the user depresses the OK button 618 on the thicknessselection screen 614 (YES in step S703), the CPU 322 determines athickness of the original placed on the ADF 101 (step S704). In the stepS704, the CPU 322 determines the thickness of the original placed on theADF 101 based on a thickness of the original set on the thicknessselection screen 614.

As a result of the determination in the step S704, when the thickness ofthe original set on the thickness selection screen 614 is “Regular”, theCPU 322 carries out the process in the step S711, which will bedescribed later. As a result of the determination in the step S704, whenthe thickness of the original set on the thickness selection screen 614is “Thin Sheet”, the CPU 322 determines whether “ON” or “OFF” isselected on the thickness selection screen 614 (step S705).

As a result of the determination in the step S705, when “ON” is selectedon the thickness selection screen 614, the CPU 322 carries out theprocess in the step S711, which will be described later, while keepingthe show-through prevention function enabled. As a result of thedetermination in the step S705, when “OFF” is selected on the thicknessselection screen 614, the CPU 322 enables the show-through preventionfunction because the show-through prevention function has been disabled(step S706). Namely, in the present embodiment, when an originaldetected by the original detecting sensor 203 is a thin sheet, theshow-through prevention function is enabled irrespective of the settingon the thickness selection screen 614. Then, the CPU 322 displays anotification screen 801 n FIG. 8A, which indicates that the show-throughprevention function has been enabled, on the LCD touch panel 500 (stepS707). After that, the CPU 322 carries out the process in the step S711,which will be described later.

As a result of the determination in the step S704, when the thickness ofthe original set on the thickness selection screen 614 is “Thick Sheet”,the CPU 322 determines whether “ON” or “OFF” is selected on thethickness selection screen 614 (step S708).

As a result of the determination in the step S708, when “OFF” isselected on the thickness selection screen 614, the CPU 322 carries outthe process in the step S711, which will be described later, whilekeeping the show-through prevention function disabled. As a result ofthe determination in the step S708, when “ON” is selected on thethickness selection screen 614, the CPU 322 disables the show-throughprevention function because the show-through prevention function hasbeen enabled (step S709). Namely, in the present embodiment, when anoriginal detected by the original detecting sensor 203 is a thick sheet,the show-through prevention function is disabled irrespective of thesetting on the thickness selection screen 614. Thus, in the presentembodiment, the show-through prevention function is controlled to beenabled or disabled based on the result of determination as to thethickness of the original in the step S704 irrespective of the settingon the thickness selection screen 614. Then, the CPU 322 displays anotification screen 802 in FIG. 8B, which indicates that theshow-through prevention function has been disabled, on the LCD touchpanel 500 (step S710). After that, the CPU 322 determines whether or notthe user has depressed the start key 507 (step S711).

As a result of the determination in the step S711, when the user has notdepressed the start key 507, the process returns to the step S701. As aresult of the determination in the step S711, when the user hasdepressed the start key 507, the CPU 322 instructs the image readingunit 103 to start reading the original (step S712). In response to theinstruction, the image reading unit 103 carries out a scanning processin FIG. 9. After that, the CPU 322 ends the present process.

FIG. 9 is a flowchart showing the procedure of the scanning processwhich is carried out by the image reading unit 103 in FIG. 3. Theprocess in FIG. 9 is implemented by the CPU 310 of the image readingunit 103 executing a program expanded from the ROM 311 into the RAM 312.

Referring to FIG. 9, the CPU 310 determines a thickness of an originalplaced on the ADF 101 (step S901). In the step S901, the CPU 310determines the thickness of the original placed on the ADF 101 based ona thickness of the original set on the thickness selection screen 614 aswith the step S704.

As a result of the determination in the step S901, when the thickness ofthe original set on the thickness selection screen 614 is “Regular”, theCPU 310 carries out a process in step S903, which will be describedlater. As a result of the determination in the step S901, when thethickness of the original set on the thickness selection screen 614 is“Thick Sheet” or “Thin Sheet”, the CPU 310 carries out a process in stepS902. In the step S902, the CPU 310 provides a notification instructingthe CPU 300 of the ADF 101 to control a conveying speed of the originalto a low speed. In response to this notification, the CPU 300 reducesthe RPM of the respective motors that drive the conveying rollers 208,the registration roller 209, the conveying roller 212, the conveyingroller 213, the large roller 211, and the sheet discharging rollers 215to a predetermined RPM. This controls the conveying speed of theoriginal from a first speed set in advance, which is a normal speed, toa second speed that is the low speed. The second speed is set at, forexample, a half of the first speed so as to enable the dischargedoriginal which is a thin sheet to entirely drop onto the dischargedsheet tray 216 and prevent a torque shortage for the original which is athick sheet in a curved area of the conveying path (conveying route) inthe ADF 101.

Then, the CPU 310 starts feeding the original (step S903) and readsimage data (step S904). The read image data is sent to the controllerunit 321 and stored in the image memory 325 through the scanner I/F 324.After that, the CPU 310 instructs the controller unit 321 to performimage processing on the image data stored in the image memory 325 (stepS905). In response to this instruction, the controller unit 321 performsvarious types of image processing on the image data stored in the imagememory 325. For example, when the show-through prevention function isenabled, the controller 321 carries out show-through removal imageprocessing in FIG. 10, which will be described later. The CPU 310 thendetermines whether or not any original is left on the original tray 201(step S906).

As a result of the determination in the step S906, when any original isleft on the original tray 201, the process returns to the step S903. Asa result of the determination in the step S906, when no original is lefton the original tray 201, the CPU 310 ends the present process.

FIG. 10 is a flowchart showing the procedure of the show-through removalimage processing which is performed by the controller unit 321 in FIG.3. The process in FIG. 10 is implemented by the CPU 322 of thecontroller unit 321 executing a program expanded from the ROM 328 intothe RAM 327.

Referring to FIG. 10, the CPU 322 reads the image data, which is storedin the image memory 325, via the scanner I/F 324 (step S1001). Next, theCPU 322 determines whether or not the show-through prevention functionis enabled (step S1002).

As a result of the determination in the step S1002, when theshow-through prevention function is not enabled, the CPU 322 ends thepresent process. As a result of the determination in the step S1002,when the show-through prevention function is enabled, the CPU 322generates a histogram from luminance levels of the image data (stepS1003). Then, the CPU 322 determines a base color level based on thegenerated histogram (step S1004). FIG. 11A shows letters 1102 showingthrough in scanned-in image data 1101. When the read image data 1101 iscomprised of a letter image on the front side and the show-throughletters 1102, a histogram 1103 in FIG. 11B, for example, is generated.In the histogram 1103, the horizontal axis represents 0 to 255, and thevertical axis represents values obtained by counting pixels atcorresponding luminance levels. The CPU 322 determines the base colorlevel based on, for example, the histogram 1103. An area from which aluminance 255 at which the density is high and which is a background isremoved, for example, a luminance level 195 designated by referencenumeral 1104 in FIG. 11B is determined as the base color level. Then,the CPU 322 sets a coefficient for removing a base color based on thebase color level determined in the step S1004. After that, the CPU 322carries out a base color removal process based on the set coefficient(step S1005). As a result, the show-through letters 1102 are removedfrom the scanned-in image data 1101 to generate image data 1105 in FIG.11C. The CPU 322 then ends the present process.

According to the embodiment described above, when an original detectedby the original detecting sensor 203 is a thin sheet, the show-throughprevention function is enabled. As a result, scanned-in image data issubjected to the show-through removal image processing, and thisprevents output of show-through data. Moreover, in the embodimentdescribed above, when an original detected by the original detectingsensor 203 is a thin sheet, the conveying speed of the original iscontrolled to the second speed lower than the first speed set inadvance. As a result, a situation in which a trailing end of theoriginal hits a leading end of a succeeding original is avoided whilethe original is being conveyed, and hence occurrence of errors such as apaper jam and poor stacking is prevented during conveyance of originals.Namely, according to the embodiment described above, output ofshow-through data is prevented while occurrence of a paper jam and poorstacking is prevented during conveyance of originals.

Furthermore, in the embodiment described above, when an originaldetected by the original detecting sensor 203 is a thick sheet, theshow-through prevention function is disabled. This prevents unnecessaryimage processing from being performed so as to remove show-through fromimage data obtained by scanning in an original which is a thick sheetunlikely to show through. As a result, a situation in which a part ofthe scanned-in image data is lost due to the image processing isavoided. Moreover, in the embodiment described above, when an originaldetected by the original detecting sensor 203 is a thick sheet, theconveying speed of the original is controlled to the second speed. Thisprevents the load on the conveying rollers in the curved area of theconveying path of the ADF 101 from becoming excessively high when athick original is being conveyed, and thus prevents occurrence of errorssuch as a paper jam and poor stacking while the thick original is beingconveyed. Namely, in the embodiment described above, occurrence of apaper jam and poor stacking is prevented during conveyance of thickoriginals while a situation in which a part of image data is lost byunnecessary image processing is avoided.

In the embodiment described above, the show-through prevention functionis controlled to be enabled or disabled based on a result ofdetermination as to a thickens of an original in the step S704irrespective of a setting made on the show-through prevention settingscreen 609 by the user. As a result. even when the user has notappropriately configured a setting on the show-through preventionfunction or when the user has forgotten to configure the setting, thesetting on the show-through prevention function is controlled to anappropriate setting suitable for a thickness of an original.

Furthermore, in the embodiment described above, in a case where the userselects the OFF button 611 on the show-through prevention setting screen609, and an original detected by the original detecting sensor 203 is athin sheet, the show-through prevention function is enabled. In thiscase, the notification screen 801 providing a notification that theshow-through prevention function has been enabled is displayed on theLCD touch panel 500. On the other hand, in a case where the user selectsthe ON button 610 on the show-through prevention setting screen 609, andan original detected by the original detecting sensor 203 is a thicksheet, the show-through prevention function is disabled. In this case,the notification screen 802 providing a notification that theshow-through prevention function has been disabled is displayed on theLCD touch panel 500. This notifies the user that for the show-throughprevention function, a setting different from a setting made on theshow-through prevention setting screen 609 by the user has been made, sothat the user can recognize a setting status of the show-throughprevention function.

It should be noted that a thickness of an original should notnecessarily be set on the thickness selection screen 614, but may be setbased on a result of detection by a sensor provided in the ADF 101. Forexample, a light transmitter and a light receiver may be placed on anoriginal conveying path in a manner holding an original between them,and a thickness of the original may be determined based on the quantityof light received through the original by the light receiver. This savesthe user from having to set a thickness via the operating unit.

Moreover, in the embodiment described above, there may be options otherthan a thick sheet, a regular sheet, and a thin sheet as choices for athickness of an original to be selected. For example, “Postcard”,“Coated Paper”, and “Copy of Ledger Sheet” may be set. For “Postcard”,the thickness can be set to a thick sheet, and for “Copy of LedgerSheet”, the thickness can be set to a thin sheet. As a result, even whenthe user does not know a thickness of an original, an appropriatethickness can be set based on a sheet type.

Furthermore, in the embodiment described above, a basis weight may beset when setting a thickness of an original. In a case where a sheettype of an original to be scanned is fixed, one of basis weights set inadvance may be selected, or a basis weight may be input on the operatingunit 326 when an original is scanned in. This makes it possible toaccurately determine a thickness of the original based on the basisweight.

Other Embodiments

Embodiment(s) of the present invention can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a‘non-transitory computer-readable storage medium’) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingunit (CPU), micro processing unit (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2018-204139, filed Oct. 30, 2018, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. An image processing apparatus comprising; a document tray; a detector that detects that a document sheet has been placed on the document tray; a display that displays an object for receiving a thickness of the document sheet from a user in response to the detector detecting that the document sheet has been placed on the document tray; a user interface that receives the thickness of the document sheet by the object from the user; a controller that controls conveyance of the document sheet by a conveyor based on information that indicates the thickness of the document sheet and that is received by the user interface; and a reader that reads an image on the document sheet conveyed by the conveyor.
 2. The image processing apparatus according to claim 1, wherein based on the information that indicates the received thickness of the document sheet, a show-through prevention function for the document sheet is enabled.
 3. The image processing apparatus according to claim 2, wherein in a case where the received thickness of the document sheet is a first type, the show-through prevention function is not enabled for the document sheet, and in a case where the received thickness of the document sheet is a sheet thinner than the first type, the show-through prevention function for the document sheet is enabled.
 4. The image processing apparatus according to claim 3, wherein in a case where the received thickness of the document sheet is the first type, the show-through prevention function for the document sheet is not enabled, and in a case where the set type of the document sheet is a sheet thicker than a second type thicker than the first type, the show-through prevention function for the document sheet is not enabled.
 5. The image processing apparatus according to claim 2, further comprising a notification unit that provides a notification that the show-through prevention function for the document sheet has been enabled.
 6. The image processing apparatus according to claim 1, wherein in a case where the received thickness of the document sheet is a first type, the controller causes the conveyer to convey the document sheet at a first conveying speed, and in a case where the received thickness of the document sheet is a sheet thinner than the first type, the controller causes the conveyer to convey the document sheet at a second conveying speed lower than the first conveying speed.
 7. The image processing apparatus according to claim 1, wherein in a case where the received thickness of the document sheet is a first type, the controller causes the conveyer to convey the document sheet at a first conveying speed, and in a case where the received thickness of the document sheet is a sheet thicker than a second type thicker than the first type, the controller causes the conveyer to convey the document sheet at a third conveying speed lower than the first conveying speed.
 8. The image processing apparatus according to claim 1, wherein the conveyer conveys the document sheet through a curved conveying path.
 9. The image processing apparatus according to claim 1, further comprising a printer that prints an image read off the document sheet by the reader.
 10. The image processing apparatus according to claim 1, further comprising a communicator that sends image data generated based on an image read off the document sheet by the reader.
 11. A control method for an image processing apparatus including a document tray, the control method comprising: detecting that a document sheet has been placed on the document tray; and displaying an object for receiving a thickness of the document sheet from a user in response to the detecting that the document sheet has been placed on the document tray; receiving at a user interface the thickness of the document sheet by the object from the user; controlling conveyance of the document sheet by a conveyor based on information that indicates the thickness of the document sheet and that is received by the user interface; and reading an image on the document sheet conveyed by the conveyor.
 12. A non-transitory computer-readable storage medium storing a program for causing a computer to execute a control method for an image processing apparatus including a document tray, the control method comprising: detecting that a document sheet has been placed on the document tray; and displaying an object for receiving a thickness of the document sheet from a user in response to the detecting that the document sheet has been placed on the document tray; receiving at a user interface the thickness of the document sheet by the object from the user; controlling conveyance of the document sheet by a conveyor based on information that indicates the thickness of the document sheet and that is received by the user interface; and reading an image on the document sheet conveyed by the conveyor. 